JP3357000B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus capable of calculating a well-known Integrated Backscatter value as an index value for evaluating tissue properties or a cyclic variation thereof (periodic variation). Related to the device.

[0002]

[Prior art and its problems] Integrated Backscatter
The (IB) value is mainly used as an index value for diagnosing and evaluating hardening and fibrosis of myocardial tissue. When calculating the IB value for a certain part of the myocardium, the power of the echo from that part is integrated in the time axis (depth) direction,
On the other hand, the power of the echo from the perfect reflector at the same depth in the aquarium is similarly integrated. Then, an IB value is defined as a ratio of the integrated values. However, there is a problem that performing reference measurement using a water tank for each measurement is complicated.

[0003] Evaluation of tissue properties using cyclic variations of IB values has also been performed. The cyclic variation is a change in the IB value corresponding to the cardiac cycle, and the range of the change is, for example, the IB value (or power integrated value) in diastole, the IB value (power integrated value) in systole, and the like. Is defined as the ratio of For example, the ratio is 6 dB in a normal person, but the ratio becomes zero or the sign is reversed when there is a disease in the myocardium.

In the conventional apparatus, when the above-mentioned IB value is obtained, the processing of averaging (integrating) the RF signal in the depth direction has been executed as described above. In this case, a high-speed A / D converter is absolutely required, and a memory for storing a large amount of data is required accordingly.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to calculate an index value for evaluating tissue properties with a simple configuration.

Another object of the present invention is to calculate the index value accurately.

[0007]

(1) In order to achieve the above object, the present invention provides a transmitting and receiving means for transmitting and receiving an ultrasonic wave, and a reception signal obtained by transmitting and receiving the ultrasonic wave. a complex signal converter for converting the signals, and power calculating means for calculating a power on the basis of the complex signal, is set
By performing integration on the power in a two-dimensional region of interest , an integral value is obtained as an index value representing the tissue characteristics.
Index value calculating means for calculating an iterated backscatter value .

According to the above configuration, the received signal is converted into a complex signal, and the power is calculated from the complex signal. In this case, for example, power is calculated as the sum of the square of the real part and the square of the imaginary part of the complex signal, and the calculated power is
The index value is integrated over a two-dimensional region of interest , thereby calculating an index value representing the tissue property. The complex signal converting means is, for example, a quadrature detector, and the power calculating means is, for example, an autocorrelator operating at lag 0. The signal after the quadrature detection is a baseband signal. As a result, the conversion speed of the A / D converter can be reduced, a relatively inexpensive A / D converter can be used, and the data amount is also reduced. Can be saved. An ultrasonic diagnostic apparatus that performs velocity measurement generally has an autocorrelator, and for example, the same circuit (autocorrelator) can be used for power calculation, or the same circuit can be time-divided into both speed calculation and power calculation. Available at As a result, manufacturing costs can be significantly reduced.

[0009]

[0010] Desirably, including the region of interest setting means for setting a region of interest on the ultrasound image.

Preferably, the apparatus includes means for calculating a fluctuation width of the periodic fluctuation by comparing two index values calculated in the diastole and the systole of the heart. Preferably, the periodic variation is a cyclic variation.

Preferably, first comparing means for comparing the magnitude of the power with a predetermined threshold, and first validity determining means for determining that the power is valid when the power is larger than the predetermined threshold. And the index value calculating means performs integration only on the power determined to be valid. The echo power from the tissue (eg, myocardium) is much higher than the echo power from the bloodstream, and by using such a phenomenon, for example, even if the blood flow is included in the region of interest, only the signal derived from the tissue is used. Can be discriminated.

Preferably, speed calculating means for calculating a speed based on the received signal, second comparing means for comparing the speed with a predetermined threshold value, and when the speed is higher than the predetermined threshold value, Second validity determining means for determining that the power is valid, wherein the index value calculating means performs integration only on the power determined to be valid. According to the above configuration, for example, the power of a moving tissue alone can be discriminated by eliminating the influence of a fixed echo such as multiple reflection.

(2) In order to achieve the above object, the present invention provides a region of interest setting means for setting a region of interest on an ultrasonic image, and a reference region for setting a reference region on an ultrasonic image. Setting means; power calculating means for calculating power from a received signal; first integrating means for integrating the power in the region of interest to calculate a power integrated value of the region of interest; and integrating the power in the reference region. second integration means for calculating a reference area power integration value and, by standardizing the region of interest power integration value in the reference region power integration value, integrated as an index value that represents the tissue state
Standardizing means for calculating a backscatter value .

According to the above configuration, since both the region of interest and the reference region can be designated in the same display frame, the complexity of the conventional method can be greatly reduced. Preferably, the region of interest is set on a myocardial region of the heart, and the reference region is set on a blood flow region of the heart. The power of the bloodstream is
This is based on the fact that it does not differ greatly between people, and changes in signal gain can be eliminated by standardization.

(3) In order to achieve the above object, the present invention provides an ROI setting means for setting a single ROI on an ultrasonic image over a blood flow site and a tissue site. Power calculating means for calculating power from the received signal; first integrating means for calculating the tissue power integrated value by integrating the power for the tissue site in the region of interest; and the power for the blood flow site in the region of interest. A second integration means for calculating a blood flow power integrated value by integrating the above, and an integrated backscatter as an index value representing tissue properties by normalizing the tissue power integrated value with the blood flow power integrated value .
And a standardization operation means for calculating a value .

According to the above configuration, a standardized index value can be calculated only by setting a single region of interest.

Preferably, the index value is calculated in consideration of each area of the tissue site and the blood flow site in the region of interest. According to this configuration, even when the areas of the tissue site and the blood flow site are different, appropriate normalization can be performed according to the difference.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration.

In FIG. 1, a probe 10 is an ultrasonic probe used in contact with the surface of a living body or inserted into a body cavity. The probe 10 has an array vibrator composed of a plurality of vibrating elements, and a two-dimensional data capturing area can be formed by electronically scanning the array vibrator. In the present embodiment, in order to extract Doppler information with high accuracy, transmission of ultrasonic pulses is performed a plurality of times (for example, 10 times) in one direction, similarly to the conventional apparatus. Therefore, when the ultrasonic pulse for forming the B-mode image is transmitted once, the ultrasonic pulse for the Doppler image is transmitted plural times in the same direction immediately before and after that. This will be repeated over the two-dimensional data acquisition area.

The transceiver 12 is a known circuit that supplies a transmission signal to the probe 10 and processes a reception signal output from the probe 10. The received signal output from the transceiver 12 is output to a display processing unit 42 described later via the detector 13. The detector 13 is a circuit that detects a received signal to form a B-mode image. Incidentally, other circuits for forming a B-mode image are not shown.

The received signal output from the transceiver 12 is
It is input to the quadrature detector 14. This quadrature detector 14
Is a well-known circuit for converting a received signal into a complex signal.
It has two mixers 16 and 18. Each mixer 16, 1
In FIG. 8, two reference signals having phases different from each other by 90 degrees are mixed with the received signal.

The A / D converters 20 and 22 are circuits for sampling each of the real part signal and the imaginary part signal constituting the complex signal, whereby the received signal is converted from an analog signal to a digital signal. You. Since this sampling is performed in the baseband region, there is no need to perform sampling in the RF signal region as in the related art. Incidentally, the mixers 16, 18 and the A / D converter 20,
A necessary low-pass filter or the like is provided between the control unit 22 and the control unit 22.

The memories 24 and 26 are storages for temporarily storing the complex signals converted into digital signals. The memories 24 and 26 store, for example, signals of a plurality of sound rays, The signal is being read.

The low-pass filter (LPF) 30 is a filter for extracting a signal component corresponding to the myocardium.
However, since the myocardial echo is much larger than the blood flow echo, it is not always necessary to provide such a low-pass filter 30. The real-part signal I and the imaginary-part signal Q output from the low-pass filter 30 are
2, 34 are input.

The autocorrelator 32 is a known circuit that calculates an autocorrelation between a plurality of received signals acquired in the same direction. In this case, the time lag between the two received signals for which the correlation is to be obtained, that is, the “lag” matches the repetition frequency T of the transmission pulse.

On the other hand, the autocorrelator 34 has basically the same configuration as the autocorrelator 32. This autocorrelator 3
4 is configured to operate with a lag of 0, that is, the autocorrelation is calculated for each signal itself, and as a result, the sum of the square of the real part and the square of the imaginary part is output. The autocorrelator 32 and the autocorrelator 34 will be described later with reference to FIG.

The speed calculator 36 is a well-known circuit that obtains a speed by calculating the argument of the two outputs X and Y output from the autocorrelator 32. The speed information obtained in this way is sent to the display processing section 42 and the comparator 3
8 has been sent. A known two-dimensional tissue Doppler image is formed using this speed information.

The comparator 38 is a circuit for comparing the speed with a predetermined threshold V _0, and outputs a signal 104 when the speed is equal to or higher than the threshold V ₀ .

The power output from the autocorrelator 34 is
The power is input to the averaging circuit 44, where the power is added for each transmission / reception direction, and the result of the addition is divided by the number of additions to obtain an average value of the power. That is, the following values are required.

[0032]

[Number 1] (1 / m) * Σ { g n (t)} 2 The above m is equivalent to the number of transmission times of the ultrasonic pulses for Doppler in the same direction, {g _n (t) ｝ ² represents the power of the received signal. Incidentally, n represents the depth of the echo data, which is a function of time t.

In the embodiment shown in FIG. 1, the averaging circuit 44 is provided. However, the power may be output directly to the arithmetic section 40 without performing such averaging.

The comparator 46 is a circuit for comparing the averaged power with a predetermined threshold P ₀ , and the power is determined by the threshold P _0.
If the above is the case, the signal 106 is output. Considering the magnitude of the speed by the comparator 38,
In calculating the IB value, it is possible to eliminate the influence of artifacts represented by multiple echoes. In addition, by taking into account the signal power by the comparator 46, there is an advantage in calculating the IB value that information on only the myocardium can be extracted even if the blood flow exists in the region of interest. These will be described later.

The arithmetic unit 40 stores the input power or the averaged power, and based on the input signal,
This is a circuit for calculating the B value. The IB value 100 is output to the display processing unit 42, and a predetermined graph is created.
The calculation unit 40 also has a function of calculating a variation width of a cyclic variation described later, and the variation width 102 is also output to the display processing unit 42. The ROI setting device 50 is a device for setting a region of interest (ROI) for calculating an IB value on a two-dimensional ultrasonic image. Here, if necessary, two ROIs are set, one of which is used as a region of interest, and the other is set as a reference region. In addition, only a single region of interest is set as needed. In this case, the calculation of the IB value is performed while using both the power of the myocardial site and the power of the blood flow region within the single region of interest. Done.

The time phase designator 52 is a device for designating time for specifying IB values to be compared with each other in a cyclic variation. For example, it specifies the IB values in diastole and systole. By the way,
The ROI setting device 50 and the time phase designator 52 are configured by input devices such as a keyboard and a trackball. Of course, such setting and designation may be automatically performed.

The display processing unit 42 is constituted by, for example, a digital scan converter (DSC) or the like. The display processing unit 42 forms a two-dimensional Doppler image, a B-mode image, an IB value graph, and the like. These images are combined with each other and output to the display 48 as one image. Incidentally, the image includes a value indicating a fluctuation range of the cyclic variation as a numerical value as necessary.

FIG. 2 shows a specific configuration example of the autocorrelator 32 shown in FIG. The circuit configuration of the autocorrelator 32 is known per se. 2, the autocorrelator 32 includes two delays 54 and 56, four mixers 58 to 64, and two adders 66 and 68. In the delays 54 and 56, a delay corresponding to one ultrasonic beam is performed, that is, autocorrelation is calculated for each depth between received signals acquired in the same direction.

The autocorrelator 34 corresponds to a circuit configuration in which the delays 54 and 56 are removed from the circuit configuration shown in FIG.
That is, it corresponds to a circuit that calculates the sum of the square of the real part and the square of the imaginary part. In this case, only the output from the adder 66 is used.

FIG. 3 shows an example of the configuration of the arithmetic unit 40 shown in FIG. The power calculated by the autocorrelator 34 or the averaged power obtained by averaging the power is input to the power integrator 70. The integration controller 72 is a circuit that determines whether or not to perform integration. The integration controller 72 outputs the signal 104 from the comparator 38 and the signal 106 from the comparator 46 as described above. Only when the power is integrated. Of course, the integration is RO
The integration controller 72 receives the ROI coordinate data and the address of each data. The memory 74 stores the power integrated value for the tissue, while the memory 76 stores the power integrated value for the blood flow. Of course, it is also possible to provide only one of the memories and store the power integration value obtained earlier in that memory.

The dividing unit 78 is a circuit for normalizing the tissue power integrated value by dividing the tissue power integrated value by the blood flow power integrated value, and obtains an IB value as an output result of the dividing unit 78. It becomes possible. The IB value is output to the display processing unit 42 as described above. The display processing unit 42 has the IB value graph creator 84 as described above, and thereby creates an IB value graph.

In the configuration example shown in FIG. 3, the calculated IB value is stored in the memory 80. Specifically, the IB value is stored in the memory 80 over a plurality of heart beats. The fluctuation range calculator 82 calculates the IB values corresponding to the two time phases designated by the time phase designator 52, and calculates the ratio of the IB values to calculate the fluctuation range of the cyclic variation. The unit of the fluctuation range is, for example, dB
It is.

FIG. 5 shows two regions of interest ROI1 and ROI2 set on the two-dimensional ultrasonic image 92. ROI1 is a region of interest to the organization and ROI2
Is a region of interest for the blood flow site, that is, a reference region.
By setting the reference area in the same frame in this way, it is possible to standardize the tissue power very easily. Incidentally, it has been confirmed that there is not much individual difference in blood flow power, and it has been proved that accurate normalization can be performed.

FIG. 6 shows a case where an IB value is calculated using a single ROI. That is, a single ROI is set so as to straddle the tissue and the blood flow in the ultrasonic image. Then, both the power integrated value for the blood flow portion and the power integrated value for the tissue are individually calculated,
As described above, the IB value is calculated by dividing the integral value of the tissue power by the integral value of the blood flow power.

FIG. 4 shows an example of the configuration of the arithmetic unit 40 when a single ROI is used. The same components as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

The tissue / blood flow discriminating section 88 discriminates between tissue and blood flow based on the speed comparison result and the power comparison result in the configuration example shown in FIG. The result of the determination is
It is input to the integration controller 72. Of course, the discrimination is performed in the ROI. For this purpose, the ROI coordinate data is input, and the coordinate data is input to the tissue / blood flow discriminating unit 8.
8 has been entered. The discrimination result is sent to the area calculation unit 90, and the area calculation unit 90 separately calculates the area of the tissue and the area of the blood flow in the same ROI. Then, the calculation result is sent to the division unit 78 in order to use it as a weight value. The dividing unit 78 normalizes the tissue power integrated value by the tissue area, executes the operation of normalizing the blood flow power integrated value by the blood flow area, and then executes the above-described division operation to obtain the IB value. I have.

According to this configuration, it is possible to automatically obtain a standardized IB value simply by setting the ROI so as to straddle the tissue and the blood flow.

FIG. 7 shows an IB value graph displayed on the display 48. The maximum peak and the minimum peak are designated on the graph by the time phase designator 52 shown in FIG. 1 (see reference numerals 94 and 96), and each designated IB
The fluctuation range of the cyclic variation is automatically calculated as the value ratio. When it is not necessary to perform the normalization based on the power integration value, the power integration result may be directly used as the IB value. However, in this case, it is necessary to standardize the tissue power integral value with the area of the ROI.

In FIG. 5, ROI1 and ROI1
2 have the same area. If the areas of the two ROIs are different, it is necessary for the division unit 78 to perform an operation to compensate for the difference.

[0050]

As described above, according to the present invention,
An index value for evaluating tissue properties can be calculated with a simple configuration, and the index value can be calculated with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a diagram illustrating a circuit configuration example of an autocorrelator.

FIG. 3 is a diagram illustrating a configuration example of a calculation unit.

FIG. 4 is a diagram illustrating another configuration example of the calculation unit.

FIG. 5 is a diagram illustrating setting of two ROIs.

FIG. 6 is a diagram illustrating setting of a single ROI.

FIG. 7 is a diagram showing an IB value graph.

[Explanation of symbols]

10 probe, 12 transceiver, 14 quadrature detector, 3
0 low-pass filter (LPF), 32, 34 autocorrelator, 36 speed calculator, 38 comparator, 40 calculator,
42 display processing unit, 44 averaging circuit, 46 comparator,
50 ROI setting device, 52 time phase designator.

Continuation of front page (56) References JP-A-8-173429 (JP, A) JP-A-2-289237 (JP, A) JP-A-8-84729 (JP, A) JP-A-4-282144 (JP) , A) Patent 2784048 (JP, B2) Patent 2647846 (JP, B2) Table 8-511184 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 8/00-8 / 15

Claims (11)

(57) [Claims] A transmitting / receiving means for transmitting / receiving an ultrasonic wave; a complex signal converting means for converting a received signal obtained by transmitting / receiving the ultrasonic wave into a complex signal; and calculating a power based on the complex signal. a power calculating means for, by executing the integration to the power at the set two-dimensional region of interest, as an index value that represents the tissue state
An index value calculating means for calculating an integrated backscatter value ; and an ultrasonic diagnostic apparatus comprising: 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said power calculation means is an autocorrelation calculator that operates with a lag of zero. 3. A device according to claim 1, the ultrasonic diagnostic apparatus characterized the early days including the region of interest setting means for setting a region of interest on the ultrasound image. 4. The apparatus according to claim 1, further comprising: means for comparing two index values calculated during diastole and systole of the heart to calculate a fluctuation width of the periodic fluctuation. Diagnostic device. 5. The ultrasonic diagnostic apparatus according to claim 4 , wherein said periodic fluctuation is a cyclic variation. 6. The apparatus according to claim 1, wherein first comparing means for comparing the magnitude of the power with a predetermined threshold value, and when the power is larger than the predetermined threshold value, the power is valid. An ultrasonic diagnostic apparatus, comprising: a first validity determining unit for determining; and wherein the index value calculating unit performs integration only on the power determined to be valid. 7. The apparatus according to claim 1, wherein a speed calculating unit that calculates a speed based on the received signal; a second comparing unit that compares the speed with a predetermined threshold; Second validity determining means for determining that the power is valid when the speed is high; and wherein the index value calculating means performs integration only on the power determined to be valid. apparatus. 8. A region of interest setting means for setting a region of interest on an ultrasonic image, a reference region setting means for setting a reference region on an ultrasonic image, and a power calculation for calculating power from a received signal Means, first integration means for integrating the power in the region of interest to calculate a power integration value of the region of interest, and second integration for integrating the power in the reference region to calculate a power integration value of the reference region. means and, Integre the region of interest power integration value normalized by the reference area power integration value, as an index value that represents the tissue state
An ultrasonic diagnostic apparatus, comprising: a standardizing operation means for calculating an iterated backscatter value . 9. The ultrasonic diagnostic apparatus according to claim 8 , wherein the region of interest is set on a myocardial part of the heart, and the reference area is set on a blood flow part of the heart. 10. A region-of-interest setting means for setting a single region of interest on an ultrasonic image over a blood flow site and a tissue site; a power calculation unit for calculating power from a received signal; A first integrating means for integrating the power for a tissue site in the region of interest to calculate a tissue power integrated value; and a second integrating means for integrating the power for a blood flow site in the region of interest to calculate a blood flow power integrated value. and second integrating means, normalized the tissue power integration value in the blood flow power integration value, integrated as an index value that represents the tissue state
An ultrasonic diagnostic apparatus, comprising: a normalization operation means for calculating a backscatter value . 11. The ultrasonic diagnostic apparatus according to claim 10 , wherein the index value is calculated in consideration of each area of a tissue part and a blood flow part in the region of interest.